1. Field of the Invention
The present invention pertains to a suspension system for use with a wheeled motor vehicle, and more particularly, it pertains to a suspension system which allows the suspended motor vehicle frame to roll transversely of the vehicle without twisting.
2. Description of the Prior Art
Prior art suspension systems for heavy duty motor vehicles generally include a rear suspension which is connected to the rear portion of the frame of the motor vehicle in at least two points along a transversely connected rear axle. The axle is usually connected to the frame or body of the vehicle by a spring suspension system of some type. A front axle can be similarly spring connected to the frame of the motor vehicle at two points which are spaced transversely across the width of the vehicle. The springs will accommodate vertical movement of the axles relative to the frame of the vehicle within predetermined limits as set by the spring structure. However, in uneven terrain the suspension system may move up and down relative to the frame of the vehicle to such an extent that the springs reach the limit of their travel thereby either causing the frame of the motor vehicle to bend or twist or causing one or more wheels to be lifted from the ground resulting in a loss of tractive effort. Even in travel over highways and streets wherein oppositely inclined surfaces are encountered the front wheels and suspension system may cause the front end of the frame to roll in one direction while the rear wheels and rear suspension system cause the rear end of the frame to roll in the opposite direction to twist the frame. This twisting of the frame of the motor vehicle can easily cause cracking or other permanent damage to the frame so that it may eventually fail. There have been many attempts to correct this problem, one of such attempts concerning the use of frames which are heavy enough so that they will not twist and distort. However, these heavy rigid frames will typically cause one or more of the wheels to be lifted off the ground while the vehicle is traveling over uneven terrain. Lifting of a wheel off of the ground causes the vehicle to lose traction and may have a significant adverse effect in both the maneuvering and propelling of the vehicle.